Light sensor having ir cut and color pass interference filter integrated on-chip

ABSTRACT

A light sensor is described that includes an IR interference filter and at least one color interference filter integrated on-chip. The light sensor comprises a semiconductor device (e.g., a die) that includes a substrate. Photodetectors are disposed proximate to the surface of the substrate. An IR interference filter is disposed over the photodetectors. The IR interference filter is configured to filter infrared light from light received by the light sensor to at least substantially block infrared light from reaching the photodetectors. At least one color interference filter is disposed proximate to the IR interference filter. The color interference filter is configured to filter visible light received by the light sensor to pass light in a limited spectrum of wavelengths (e.g., light having wavelengths between a first wavelength and a second wavelength) to at least one of the photo detectors.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation under 35 U.S.C. §120 of U.S.patent application Ser. No. 13/187,729, filed Jul. 21, 2011, entitled“LIGHT SENSOR HAVING IR CUT AND COLOR PASS INTERFERENCE FILTERINTEGRATED ON-CHIP;” which claims priority under 35 U.S.C. §119(e) ofU.S. Provisional Application Ser. No. 61/436,510 filed Jan. 26, 2011,entitled “LIGHT SENSOR HAVING IR CUT AND COLOR INTERFERENCE FILTERINTEGRATED ON-CHIP.” U.S. patent application Ser. No. 13/187,729 andU.S. Provisional Application Ser. No. 61/436,510 are hereby incorporatedby reference in their entireties.

BACKGROUND

Electronic devices, such as smart phones, tablet computers, digitalmedia players, and so forth, increasingly employ light sensors tocontrol the manipulation of a variety of functions provided by thedevice. For example, light sensors may be used by an electronic deviceto detect ambient lighting conditions in order to control the brightnessof the device's display screen. Typical light sensors employphotodetectors such as photodiodes, phototransistors, or the like, whichconvert received light into an electrical signal (e.g., a current orvoltage). However, the response of such photodetectors can be influencedby the presence of infrared (IR) light (i.e., electromagnetic radiationhaving a wavelength greater than approximately 700 nanometers (nm) thatcan be detected by the photodetector). For example, a light sensor of anelectronic device may indicate that the surrounding ambient environmentis “brighter” than it really is because the surrounding lightedenvironment contains a larger proportion of infrared light than normal,such as where the surrounding lighted environment is furnished byartificial lighting, and so forth.

SUMMARY

A light sensor is described that includes an IR interference filter andat least one color interference filter integrated on-chip (i.e.,integrated on the die of the light sensor). In one or moreimplementations, the light sensor comprises a semiconductor device(e.g., a die) that includes a substrate. Photodetectors (e.g.,photodiodes, phototransistors, etc.) are disposed proximate to thesurface of the substrate. An IR interference filter is disposed over thephotodetectors. The IR interference filter is configured to filterinfrared light from light received by the light sensor to at leastsubstantially block infrared light from reaching the photodetectors. Atleast one color interference filter is disposed above or below the IRinterference filter. The color interference filter is configured tofilter visible light received by the light sensor to pass light in alimited spectrum of wavelengths (e.g., light having wavelengths betweena first wavelength and a second wavelength) to at least one of thephotodetectors. The photodetectors may also comprise one or more clearphotodetectors configured to receive light that is not filtered by acolor interference filter, thereby allowing the clear photodetector todetect the ambient light environment.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

DRAWINGS

The detailed description is described with reference to the accompanyingfigures. The use of the same reference numbers in different instances inthe description and the figures may indicate similar or identical items.

FIG. 1A is a diagrammatic partial cross-sectional side view illustratinga light sensor comprised of a semiconductor device having a plurality ofphotodetectors, an IR cut interference filter, a plurality of colorinterference filters, and a clear photodetector in accordance with anexample implementation of the present disclosure.

FIG. 1B is a diagrammatic partial cross-sectional side view illustratinga light sensor comprised of a semiconductor device having a plurality ofphotodetectors, an IR cut interference filter, and a plurality of colorinterference filters, wherein clear photodetectors are positionedbetween the color interference filters to form clear sensors.

FIG. 1C is a diagrammatic partial cross-sectional side view illustratingthe light sensor comprised of a semiconductor device having a pluralityof photodetectors, an IR cut interference filter, a plurality of colorinterference filters, and a dark mirror covering the periphery of the IRcut interference filter and/or other light transmitting edges inaccordance with an example implementation of the present disclosure.

FIG. 1D is a diagrammatic partial cross-sectional side view illustratingthe light sensor comprised of a semiconductor device having a pluralityof photodetectors, an IR cut interference filter, a plurality of colorinterference filters, and a dark mirror in accordance with an exampleimplementation of the present disclosure.

FIG. 1E is a diagrammatic partial cross-sectional side view illustratingthe light sensor comprised of a semiconductor device having a pluralityof photodetectors, an IR cut interference filter, a plurality of colorinterference filters, and a dark mirror covering the periphery of the IRcut interference filter and/or other light transmitting edges (e.g.,color interference filters) color in accordance with an exampleimplementation of the present disclosure.

FIG. 1F is a diagrammatic partial cross-sectional side view illustratingthe light sensor comprised of a semiconductor device having a pluralityof photodetectors, an IR cut interference filter, a plurality of colorinterference filters, and a dark mirror (e.g., color interferencefilters) in accordance with an example implementation of the presentdisclosure.

FIG. 2A is a diagrammatic top plan view illustrating an implementationof the light sensor depicted in FIG. 1A.

FIG. 2B is a diagrammatic top plan view illustrating a secondimplementation of the light sensor depicted in FIG. 1B, illustrating theplacement of clear photodetectors in areas of the substrate between thecolor interference filters.

FIG. 2C is a diagrammatic plan view illustrating the application of adark mirror to the light sensor shown in FIG. 2A.

FIG. 2D is a diagrammatic plan view illustrating the application of adark mirror to the light sensor shown in FIG. 2B.

FIG. 3 is a flow diagram illustrating a process in an exampleimplementation for fabricating a light sensor in accordance with thepresent disclosure.

DETAILED DESCRIPTION

Overview

To filter infrared light, light sensors may employ infrared blockingfilters to reduce the transmission of infrared light, while passingvisible light to the photodetector array of the light sensor. Such IRblocking filters are comprised of IR cut material applied externally tothe light sensor package following fabrication of the package. Thisconfiguration effectively blocks infrared light from reaching thephotodiodes, but also substantially reduces the amount of infrared lightthat reaches the infrared photodetectors of the light sensor.Consequently, the sensitivity of the resulting light sensor to infraredlight is reduced.

Accordingly, a light sensor is described that includes an IR cut and atleast one color interference filter integrated on-chip (i.e., integratedon the die of the light sensor). In this manner, the IR cut interferencefilter may be patterned so that it does not block infrared light toinfrared photodetectors of the light sensor. In one or moreimplementations, the light sensor is fabricated as a semiconductordevice that comprises a die having a substrate. Photodetectors such asphotodiodes, phototransistors, or the like, are formed in the substrateproximate to the surface of the substrate. The IR cut interferencefilter is disposed on the surface of the substrate over thephotodetectors. The IR cut interference filter is configured to filterinfrared light from light received by the light sensor to at leastsubstantially block infrared light from reaching the photodetectors.However, by forming the IR cut interference filter on the substrate, theIR cut interference filter may be patterned so that it does not blockinfrared light to infrared photodetectors of the light sensor. One ormore color interference filters are disposed proximate to the IR cutinterference filter. For example, color interference filters (e.g., red,green, blue filters) may be formed on the IR cut interference filter oron the surface of the substrate under the IR cut interference filter.The color interference filters are configured to filter visible lightreceived by the light sensor to pass light in a limited spectrum ofwavelengths (e.g., light having wavelengths between a first wavelengthand a second wavelength) to at least one of the photodetectors. Thephotodetectors may also comprise one or more clear photodetectorsconfigured to receive light that is not filtered by a color interferencefilter, thereby allowing the clear photodetector to detect the ambientlight environment. In implementations, the clear photodetectors may bepositioned between color interference filters to reduce the siliconimplementation area of the light sensor. In at least one implementation,a dark mirror may be formed about the periphery of the IR cutinterference filter. The dark mirror is configured to at leastsubstantially eliminate impingement of light onto the photodetectorsthat does not pass through the IR cut interference filter.

In the following discussion, example implementations of light sensorsthat include an IR cut interference filter and at least one colorinterference filter integrated on-chip are first described. Exampleprocedures are then discussed that may be employed to fabricate theexample light sensor.

Example Implementations

FIGS. 1A through 1F, illustrate light sensors 100 in accordance with anexample implementation of the present disclosure. As shown, the lightsensors 100 comprise semiconductor devices that include a die having asubstrate 102. The substrate 102 furnishes a base material utilized toform one or more electronic devices through various fabricationtechniques such as photolithography, ion implantation, deposition,etching, and so forth. The substrate 102 may comprise n-type silicon(e.g., silicon doped with a group V element (e.g., phosphorus, arsenic,antimony, etc.) to furnish n-type charge carrier elements to thesilicon) or p-type silicon (e.g., silicon doped with a group IIIAelement (e.g., boron, etc.) to furnish p-type charge carrier elements tothe silicon).

The substrate 102 of each light sensor 100 is illustrated as having atop surface 104 and a bottom surface 106. An array of photodetectors(photodetectors 108, 112 are shown) is formed in the substrate 102proximate to the top surface 104. The photodetectors 108, 112 within thearray may be configured in a variety of ways. For example, thephotodetectors 108, 112 may be comprised of a photo sensor diode, aphototransistor, or the like. In an implementation, the photodetectors108, 112 are capable of detecting a light and providing a signal inresponse thereto. The photodetectors 108, 112 may provide a signal byconverting light into current or voltage based upon the intensity of thedetected light. Thus, once a photodetector is exposed to light, multiplefree electrons may be generated to create a current. The photodetectors108, 112 are configured to detect light in both the visible lightspectrum and the infrared light spectrum. As used herein, the term lightis contemplated to encompass electromagnetic radiation occurring in thevisible light spectrum and the infrared light spectrum. The visiblelight spectrum (visible light) includes electromagnetic radiationoccurring in the range of wavelengths from approximately three hundredand ninety (390) nanometers to approximately seven hundred and fifty(750) nanometers. Similarly, the infrared light spectrum (infraredlight) includes electromagnetic radiation that ranges in wavelength fromapproximately seven hundred (700) nanometers to approximately threehundred thousand (300,000) nanometers. In implementations, complimentarymetal-oxide-semiconductor (CMOS) fabrication techniques may be utilizedto form the photodetectors 108, 112.

An IR cut interference filter 110 is illustrated as formed over thephotodetectors 108 on the top surface 104 of the substrate 102. The IRcut interference filter 110 is configured to filter infrared light fromlight received by the light sensor 100 to at least substantially blockinfrared light from reaching the photodetectors 108. The IR cutinterference filter 110 may further be configured to at leastsubstantially pass visible light (i.e., light in the visible spectrum)received by the light sensor 100 to the photodetectors 108. Forinstance, in an example implementation, an IR cut interference filter110 may be provided that is capable of blocking approximately fifty (50)to one hundred (100) percent of infrared light (e.g., light in theinfrared spectrum) incident on the photodetectors 108 while at leastsubstantially passing (e.g., passing greater than approximately fifty(50) percent) visible light (e.g., light in the visible spectrum) to thephotodetectors 108. However, the aforementioned values (e.g., percentagevalues representing the proportion of infrared light blocked and/orpassed by the IR cut interference filter 110) may depend on particularapplication requirements of the light sensor 100. Moreover, IR cutinterference filters 110 that are capable of blocking a higher or lowerproportion of infrared light and/or of transmitting a higher or lowerproportion of visible light are contemplated.

The IR cut interference filter 110 may be configured in a variety ofways. In an implementation, the IR cut interference filter 110 maycomprise a multi-layer structure that includes at least two differentmaterials of different refractive indices. The IR cut interferencefilter 110 may be approximately five (5) to fifteen (15) microns thickand/or approximately seventy (70) to one hundred twenty (120) layersthick. In a specific implementation, the IR cut interference filter 110may be approximately ten (10) microns thick and/or approximately ninety(90) to one hundred (100) layers thick. However, it is contemplated thatthe IR cut interference filter 110 may have other constructions (e.g.,number of layers) and/or thicknesses. Moreover, although a single IR cutinterference filter 110 is illustrated, it is contemplated that thelight sensor 100 may be provided with multiple IR cut interferencefilters 110.

In at least some implementations, the light sensor 100 may be configuredto include one or more infrared photodetectors 112 (i.e., photodetectors108 that are configured to detect light in the infrared spectrum formedin the substrate 102 of the light sensor 100 die). These photodetectors112 detect infrared light (i.e., light in the infrared spectrum) thatmay, for example, be transmitted by an infrared transmitter (e.g., aninfrared light emitting diode (LED)) as part of a proximity sensorimplemented in the electronic device. Accordingly, the IR cutinterference filter 110 may be patterned so that it does not block thereception of infrared light (i.e., light in the infrared spectrum) bythe infrared photodetectors 112, thereby increasing the sensitivity ofthe light sensor to infrared light and improving the performance ofdevices that employ the light sensor 100 (e.g., the proximity sensor inan electronic device).

Color interference filters 114 are illustrated proximate to the IR cutinterference filter 110. The color interference filters 114 areconfigured to filter visible light received by the light sensor 100 topass light in a limited spectrum of wavelengths (e.g., light havingwavelengths between a first wavelength and a second wavelength) to atleast one of the photodetectors 108. In one implementation, the colorinterference filters 114 allow visible light in a limited spectrum ofwavelengths to pass through the filter, while blocking (e.g.,reflecting) visible light within a second spectrum of wavelengths. Thus,the color interference filters 114 may be substantially transparent forvisible light within a first spectrum of wavelengths, and substantiallyopaque within a second spectrum of wavelengths. In implementations, thecolor interference filters 114 may comprise multilayer structures havingvaried thicknesses and/or numbers of layers, which may have differingthicknesses and/or refractive indices.

A plurality of color interference filters 114 may be employed. Forexample, the light sensor 100 may comprise a first color interferencefilter 114 a configured to filter visible light and pass light having afirst limited spectrum of wavelengths (e.g., wavelengths between a firstwavelength and a second wavelength), a second color interference filter114 b configured to filter visible light and pass light having a secondlimited spectrum of wavelengths (e.g., wavelengths between a thirdwavelength and a fourth wavelength), and a third color interferencefilter 114 c configured to filter visible light and pass light having athird spectrum of wavelengths (e.g., wavelengths between a fifthwavelength and a sixth wavelength), and so forth. In the exampleillustrated, the light sensor 100 is comprised of an array of threedifferent color interference filters 114: a first (blue) colorinterference filter 114 a configured to transmit a “blue” visible light(i.e., visible light with a wavelength between approximately fourhundred fifty (450) nanometers and approximately four hundredseventy-five (475) nanometers); a second (green) color interferencefilter 114 b configured to transmit a “green” visible light (i.e.,visible light with a wavelength between approximately four hundredninety-five (495) nanometers and approximately five hundred and seventy(570) nanometers); and a third (red) color interference filter 114 cconfigured to transmit a “red” visible light (i.e., visible light with awavelength between approximately six hundred and twenty (620) nanometersand approximately seven hundred and fifty (750) nanometers). It iscontemplated that other visible light color interference filters 114 maybe employed. For instance, color interference filters 114 configured totransmit visible light having limited spectrums of wavelengths typicallyassociated with the colors of cyan, magenta, yellow, and so forth, maybe provided. The color interference filters 114 are selectively arrayedover photodetectors 108 to allow visible light in a desired limitedspectrum of wavelengths to be passed to the photodetectors 108. Forexample, as shown in FIGS. 1A and 1B, the first color interferencefilter 114 a is positioned over a first photodetector 108 a, the secondcolor interference filter 114 b is positioned over a secondphotodetector 108 b, and the third filter 112 c is positioned over athird photodetector 108 c.

In the implementations illustrated in FIGS. 1A and 1B, the colorinterference filters 114 are formed on the outer surface of the IR cutinterference filter 110. However, it is contemplated that, in otherimplementations, the color interference filters 114 may be formed on thesurface 104 of the substrate 102 directly over one or more correspondingphotodetectors 108. The IR cut interference filter 110 is thus formed onthe surface 104 of the substrate 102 over the color interference filters108, and would at least substantially cover the color interferencefilters 114 upon completion of the fabrication process. In an exampleimplementation, the color interference filters 114 have a thickness ofapproximately five (5) microns. However, it is contemplated that colorinterference filters 114 having lesser or greater thicknesses arepossible.

The array of photodetectors 108 may further include one or more clearphotodetectors 116 configured to receive light that is not filtered by acolor interference filter 114. As illustrated, the clear photodetectors116 may be positioned in the substrate 102 so that they are positionedunder the IR cut interference filter 110 but are not located below acolor interference filter 114. Thus, the clear photodetectors 116 detectlight within a spectrum of wavelengths corresponding to several visiblecolors (i.e., light from the visible spectrum). In this manner, theclear photodetectors 116 may be used to detect visible ambient lightingconditions absent infrared interference.

The clear photodetectors 116 may be configured in a variety of ways. Forexample, like the other photodetectors 112 within the array, the clearphotodetectors 114 may comprise a photodiode, a phototransistor, or thelike, that is capable of detecting a light by converting light intocurrent or voltage. In an implementation, the signal (e.g., current orvoltage) produced by the clear photodetectors 116 is based upon (e.g.,proportional to) the detected intensity of visible light received. Thus,the clear photodetectors 116 may be used to detect the intensity of theambient light level outside of a portable electronic device (not shown)in which the light sensor 100 is integrated. The resulting measure ofambient light intensity may be utilized by various applications runningin the portable electronic device. For example, an application of theportable electronic device may control the brightness of a displayscreen based upon the ambient light intensity.

As discussed above, the clear photodetectors 116 may be arrayed with thephotodetectors 108 which receive light that passes through a colorinterference filter 114. In the implementation illustrated in FIGS. 2Aand 2C, the clear photodetectors 116 are shown positioned in one or morecells (clear sensor cells 202) that are arrayed with cells (color sensorcells 204) containing photodetectors 108 which receive light that passesthrough a color interference filter 114. Thus, in the implementationillustrated, the light sensor 100 may include an array 206 of cells 202,204 having one or more clear sensor cells 202 that do not include acolor interference filter 114, one or more first color sensor cells 204a that comprise a first color interference filter 114 a (e.g., a bluecolor interference filter), one or more second color sensor cells 204 bthat comprise a second color interference filter 114 b (e.g., a greencolor interference filter), one or more third cells that comprise athird color interference filter 114 c (e.g., a red color interferencefilter), and so forth. As noted above, it is contemplated that a widevariety of visible light color interference filters 114 may be employedby the light sensor 100. Thus, color sensor cells 204 may comprise colorinterference filters 114 configured to transmit light having colors ofcyan, magenta, yellow, and so forth.

Spacing exists between the color interference filters 114 due to therequirements of fabrication processes (e.g., lithography) used in theirformation. For instance, in an example array 206, between approximatelytwenty (20) to approximately forty (40) microns of “empty” space(channels) may be left between each color interference filter 114 (e.g.,between each color cell 204) and other color interference filters 114(e.g., other color cells 204), or other circuit elements of the lightsensor 100. In the implementation shown in FIGS. 1B through 1F, 2B, and2D, the clear photodetectors 114 are positioned to utilize this emptyspace. For example, in the example implementation shown in FIGS. 1Bthrough 1F, a clear photodetector 116 may be positioned between thefirst photodetector 108 a and the second photodetector 108 b. Similarly,a second clear photodetector 116 may be positioned between the secondphotodetector 108 b and the third photodetector 108 c. The clearphotodetectors 116 are covered by the IR cut interference filter 110.

The clear photodetectors 116 may thus be positioned in the “empty”channels 206 between color cells 204 (i.e., cells comprising colorinterference filters 114) as shown in FIGS. 2B and 2D. The clearphotodetectors 116 may also be positioned proximate to the outside edgesof array 208. Thus, an array 208 is formed wherein the clear sensor cell202 (e.g., clear photodetectors 116) is interlaced between multiplecolor sensor cells 204 (i.e., between the color interference filters114). This array 208 provides greater utilization of the surface area ofthe substrate 202. For instance, in one example, area utilization by animplementation employing the array 208 shown in FIG. 2B and 2D was tenpercent (10%) greater than that of an implementation configured with thearray 206 shown in FIG. 2A and 2C.

In FIGS. 1C through 1F and FIGS. 2C through 2D, light sensors 100 areillustrated that further include a dark mirror 118 configured tosubstantially eliminate impingement of light on the photodetectors 108that does not pass through the IR cut interference filter 110. The darkmirror 118 may be constructed from opaque dielectric materials in such away that does not transmit and reflects light (visible light andinfrared light). As shown, the dark mirror 118 is positioned about theperiphery of the IR cut interference filter 110 (e.g., proximate toedges 212, 214, 216, 218 of the array 208). However, in otherimplementations, the dark mirror 118 can also cover the edge of thecolor interference filters 114.

In various implementations, the light sensors 100 described herein maybe configured to detect a surrounding light environment and/or toprovide infrared light detection (e.g., for use as a proximity sensor).The color interference filters 114 are configured to filter visiblelight and pass light in a limited spectrum of wavelengths to therespective photodetectors 108. The photodetectors 108 generate a signal(e.g., current value) based upon the intensity of the light. The IR cutinterference filter 110 is configured to filter infrared light tosubstantially block infrared light from reaching the photodetectors 108.The clear photodetectors 114 detect ambient lighting conditions absentcolor filtration and generate a signal (e.g., a current value) basedupon the intensity of visible light detected. The signal generated bythe photodetectors 108 that receive filtered light and the clearphotodetectors 114 may be utilized by other circuit devices and/orapplications to control various aspects of a portable electronic device(e.g., control the brightness of the device's display screen, to turnoff backlighting to conserving battery life, and so forth). Infraredphotodetectors 114 may detect infrared light (i.e., light in theinfrared spectrum) that may, for example, be transmitted by an infraredtransmitter (e.g., an infrared light emitting diode (LED)) as part of aproximity sensor implemented in the electronic device. The IR cutinterference filter 110 may be patterned so that it does not block thereception of infrared light by the infrared photodetectors 114, therebyincreasing the sensitivity of the light sensor to infrared light andimproving the performance of devices that employ the light sensor 100.

Example Fabrication Process

The following discussion describes example techniques for fabricating alight sensor that includes an IR cut interference filter and at leastone color interference filter integrated on-chip (i.e., integrated onthe die of the light sensor). In the implementation described below, thelight sensor is fabricated utilizing back-end complementarymetal-oxide-semiconductor (CMOS) processing techniques. However, it iscontemplated that light sensors in accordance with the presentdisclosure may be fabricated using other semiconductor chipfabrication/packaging technologies, such as wafer-level packaging (WLP),and so on.

FIG. 3 depicts a process 300, in an example implementation, forfabricating a light sensor, such as the example light sensors 100illustrated in FIGS. 1A through 2D and described above. In the process300 illustrated, a plurality of photodetectors are formed in a substrateof a wafer proximate to the surface of the substrate (Block 302). Thesubstrate of the wafer may comprise n-type silicon (e.g., silicon dopedwith a group V element (e.g., phosphorus, arsenic, antimony, etc.) tofurnish n-type charge carrier elements to the silicon) or p-type silicon(e.g., silicon doped with a group IIIA element (e.g., boron, etc.) tofurnish p-type charge carrier elements to the silicon). Thus, thesubstrate furnishes a base material utilized to form the photodetectorsas well as other electronic devices of the light sensor. Thephotodetectors may comprise photodiodes, phototransistors, or the like,formed in the substrate of the wafer using suitable fabricationtechniques such as photolithography, ion implantation, deposition,etching, and so forth. In one or more implementations, at least onephotodetector of the plurality of photodetectors may comprise aninfrared photodetector that is configured to detect an infrared light(light in the infrared spectrum).

An IR cut interference filter is next formed over the surface of thesubstrate 102 (Block 304). In one or more implementations, the IR cutinterference filter may be deposited on the surface of the substrateover the photodetectors (Block 306) using a suitable depositiontechnique. The IR cut interference filter may further be patterned sothat it does not block the reception of infrared light (i.e., light inthe infrared spectrum) by infrared photodetectors formed in thesubstrate, as described in the discussion of Block 302. For instance, inan example implementation, the IR cut interference filter may comprise amulti-layer structure that includes two different materials that eachhas a different refractive index to create an interference effect toblock infrared light. In such implementations, the various layers of theIR cut interference filter may be formed on a wafer using sputteringdeposition techniques and patterned using resist lift-off techniques.However, it is contemplated that other techniques may also be employed.These techniques may include, but are not limited to: magnetronsputtering, chemical vapor deposition (CVD), electrochemical deposition(ECD), molecular beam epitaxy (MBE), and atomic layer deposition (ALD).When formed, the IR cut interference filter may be approximately five(5) to fifteen (15) micros thick and/or approximately seventy (70) toone hundred and twenty (120) layers thick. However, it is contemplatedthat the IR cut interference filter may have other constructions and/orthicknesses.

One or more color interference filters 112 are formed proximate to theIR cut interference filter (Block 308). In an implementation, the colorinterference filters are deposited on the outer surface of the IR cutinterference filter using suitable deposition techniques (Block 310).However, it is contemplated that, in other implementations, the colorinterference filters may be formed on the surface of the substratedirectly over one or more corresponding photodetectors prior toformation of the IR cut interference filter. The IR cut interferencefilter may then be formed on the surface of the substrate over the colorinterference filters, so that the IR cut interference filter at leastsubstantially covers the color interference filters. The colorinterference filters may be aligned with a respective photodetector tofilter light received by that photodetector. When formed, the colorinterference filters may have a thickness of approximately five (5)microns. However, it is contemplated that color interference filtershaving lesser or greater thicknesses are possible. The colorinterference filters may be fabricated using methodology and/ortechniques that are the same as, or similar to, those used to form theIR cut interference filter.

In one or more implementations, a dark mirror may be provided about theperiphery of the IR cut interference filter and/or the periphery of thecolor interference filters (Block 118) to substantially eliminateimpingement of light on the photodetectors that does not pass throughthe IR cut interference filter (and/or the color interference filters).The dark mirror is formed of opaque materials (e.g., metal/oxidemultilayer, or the like) that do not transmit light (visible light andinfrared light). The dark mirror may be formed using a variety oftechniques, such as via the deposition/patterning techniques, and soforth. For example, sputtering and photo-resist lift-off techniques maybe utilized to form the dark mirror.

As noted, the light sensor may be fabricated utilizing back-endcomplementary metal-oxide-semiconductor (CMOS) processing techniques.Thus, the photodetectors, the color interference filters, and the IR cutinterference filter may be formed at wafer level. The wafer isthereafter diced into one or more dies, and each die packagedindividually to form a light sensor. The wafer may also be furtherprocessed following formation of the photodetectors, color interferencefilters, and IR cut interference filter using wafer-level packaging(WLP) techniques and diced to form one or more light sensors.

Conclusion

Although the subject matter has been described in language specific tostructural features and/or process operations, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described above.Rather, the specific features and acts described above are disclosed asexample forms of implementing the claims.

What is claimed is:
 1. A light sensor comprising: a substrate having asurface; a plurality of photodetectors disposed proximate to thesurface, each of the plurality of photodetectors configured to detectlight and to provide a signal in response thereto; an IR cutinterference filter disposed over the surface and configured to filterinfrared light to at least substantially block infrared light fromreaching the plurality of photodetectors; and at least one colorinterference filter disposed proximate to the IR cut interferencefilter, the at least one color interference filter configured to filtervisible light to pass light in a limited spectrum of wavelengths to atleast one photodetector of the plurality of photodetectors.
 2. The lightsensor as recited in claim 1, wherein at least one of the plurality ofphotodetectors comprises a clear photodetector, the clear photodetectorconfigured to receive light unfiltered by a color interference filter todetect an ambient light environment.
 3. The light sensor as recited inclaim 1, wherein the IR cut interference filter is deposited on thesurface of the substrate over the plurality of photodetectors and the atleast one color interference filter is deposited on the IR cutinterference filter.
 4. The light sensor as recited in claim 1, whereinthe at least one color interference filter is deposited on the surfaceof the substrate and the IR cut interference filter is deposited on thesurface of the substrate over the photodetectors and the at least onecolor interference filter.
 5. The light sensor as recited in claim 1,wherein the photodetectors comprise at least one of photodiodes orphototransistors.
 6. The light sensor as recited in claim 1, furthercomprising a dark mirror disposed about a periphery of the IR cutinterference filter, the dark mirror configured to at leastsubstantially eliminate impingement of light that does not pass throughthe IR cut interference filter onto the plurality of photodetectors. 7.The light sensor as recited in claim 6, further comprising the darkmirror disposed about a periphery of the at least one color interferencefilter, the dark mirror configured to at least substantially eliminateimpingement of light that does not pass through the IR cut interferencefilter onto the plurality of photodetectors.
 8. A light sensorcomprising: a substrate having a surface; a plurality of photodetectorsdisposed proximate to the surface, the plurality of photodetectorsconfigured to detect light; an IR interference filter disposed over thesurface and configured to at least substantially block transmission ofinfrared light to the plurality of photodetectors; a first colorinterference filter disposed proximate to the IR interference filter andconfigured to filter visible light to pass visible light in a firstlimited spectrum of wavelengths to at least a first one of the pluralityof photodiodes; a second color interference filter disposed proximate tothe IR interference filter and configured to filter visible light topass visible light in a second limited spectrum of wavelengths to atleast a second one of the plurality of photodiodes; and a third colorinterference filter disposed proximate to the IR interference filter andconfigured to filter visible light to pass visible light in a thirdlimited spectrum of wavelengths to at least a third one of the pluralityof photodiodes.
 9. The light sensor as recited in claim 8, wherein theplurality of photodetectors comprises at least one clear photodetector,the clear photodetector configured to detect visual light that is notfiltered by the first color interference filter, the second colorinterference filter, or the third color interference filter.
 10. Thelight sensor as recited in claim 8, wherein the at least one clearphotodetector is positioned between the first color interference filterand the second color interference filter or between the second colorinterference filter and the third color interference filter.
 11. Thelight sensor as recited in claim 8, wherein the plurality ofphotodetectors further comprise an infrared photodetector that isconfigured to detect infrared light.
 12. The light sensor as recited inclaim 11, wherein the IR interference filter is patterned so that the IRinterference filter does not filter light received by the infraredphotodetector.
 13. The light sensor as recited in claim 8, wherein thefirst limited spectrum of wavelengths comprises wavelengths fromapproximately 450 nm to approximately 475 nm, the second limitedspectrum of wavelengths comprises wavelengths from approximately 495 nmto approximately 570 nm, and the third limited spectrum of wavelengthscomprises wavelengths from approximately 620 nm to approximately 750 nm.14. The light sensor as recited in claim 8, further comprising a darkmirror disposed about a periphery of the IR interference filter, thedark mirror configured to at least substantially eliminate impingementof light that does not pass through the IR interference filter onto theplurality of photodetectors.
 15. The light sensor as recited in claim14, further comprising the dark mirror formed about a periphery of thefirst color interference filter, a periphery of the second colorinterference filter, and a periphery of the third color interferencefilter, the dark mirror configured to at least substantially eliminateimpingement of light that does not pass through the IR interferencefilter onto the plurality of photodetectors.
 16. A process comprising:providing a plurality of photodetectors proximate to a substrate, eachof the plurality of photodetectors configured to detect light and toprovide a signal in response thereto; providing an IR cut interferencefilter over the surface, the IR cut interference filter configured tofilter infrared light to at least substantially block infrared lightfrom reaching the plurality of photodetectors; and providing at leastone color interference filter proximate to the IR cut interferencefilter, the at least one color interference filter configured to filtervisible light to pass light in a limited spectrum of wavelengths to atleast one photodetector of the plurality of photodetectors.
 17. Theprocess as recited in claim 16, wherein providing of the IR cutinterference filter comprises depositing the IR cut interference filteron the surface of the substrate over the photodetectors; and whereinproviding of the at least one color interference filter proximate to theIR cut interference filter comprises depositing the at least one colorinterference filter on the IR cut interference filter.
 18. The processas recited in claim 16, wherein providing of the at least one colorinterference filter proximate to the IR cut interference filtercomprises depositing the at least one color interference filter on thesurface of the substrate, and wherein providing of the IR cutinterference filter comprises depositing the IR cut interference filteron the surface of the substrate over the photodetectors and the at leastone color interference filter.
 19. The process as recited in claim 18,further comprising patterning the IR cut interference filter.
 20. Theprocess as recited in claim 16, further comprising providing a darkmirror about a periphery of the IR interference filter, the dark mirrorconfigured to at least substantially eliminate impingement of light thatdoes not pass through the IR interference filter onto the plurality ofphotodetectors.